The objective of this application is to obtain funds to open and maintain an animal facility for members of the Cancer Center. Such a facility is needed because infectious agents, and rodent viruses in particular, affect immune functions and animal survival in an uncontrollable manner; natural killer (NK) activity, macrophage functions, tumor resistance, and other immune responses in vivo can be drastically altered by infectious agents. Equally important is the fact that the establishment, growth, and function of T-cell lines in vitro can be drastically altered when "filler cells" come from mice that have various subclinical infections. Furthermore, experiments testing (or depending upon) latency of virus infections can be seriously affected by intercurrent infections with other viruses. Finally, nude mice are essential for cancer research and must be bred and maintained in an environment that is free of pathogens. The plan is for a double-corridor animal facility with nine animal rooms containing a total of 28 "Illinois cubicles." The design is based on the experience of other facilities. Because successful operation will depend entirely on very careful and knowledgeable supervision, the facility will be under the direction of a specially trained supervisor who has experience with the biology of rodent viruses and other important murine pathogens. The supervisor in consultations with the veterinarian, will oversee the microbiological testing and will strictly enforce and examine the effectiveness of the guidelines and procedures that must be followed by both the animal caretaker and the investigators using the facility. The high quality of the animal facility will increase the quality of the information obtained from animal experimentation. This in turn will (1) prevent many wasted experiments, (2) lead to more efficient use of research funds, and (3) reduce the number of animals that must be used in experiments.